Source

ERC is an IRC client for Emacs
The documentation is kept on the Emacs Wiki:
* http://www.emacswiki.org/cgi-bin/wiki.pl?EmacsIRCClient
Quick start:
Put all the files in your load-path*, and add the following
to your ~/.emacs:
(require 'erc)
*Don't know what a load path is? See:
http://www.emacswiki.org/cgi-bin/wiki.pl?LoadPath
Usage:
Use M-x erc-select to connect to a server. You can connect to
multiple servers.
Customization:
Use M-x customize-group RET erc RET to get an overview of all the
variables you can tweak.